The immunochemical properties of gastrointestinal mucin-type glycoproteins will be examined to determine the potential of these glycoproteins as organ-specific markers and to determine the extent of their biochemical and immunologic relatedness. Mucins have been purified from the various anatomic regions of the gastrointestinal tract, and antisera raised against each individual mucin. Radioimmunoassays will be developed for each mucin and employed for heterologous inhibition studies in order to examine immunochemical relatedness between individual mucin preparations. In addition, the biochemical nature of the immunodeterminants will be probed employing specific partial degradation of the mucins followed by determination of remaining immunologic reactivity. The potential role of the glycoproteins as tissue markers will be analyzed by a retrospective study of biopsy specimens from individuals with benign and malignant disorders of both gastrointestinal and extragastrointestinal tissues. (AG)